1. Technical Field
The present invention relates to a polarizing element, a method for producing the polarizing element, a liquid crystal device, an electronic apparatus, and a projection display.
2. Related Art
A variety of electro-optical apparatuses use a liquid crystal device as a light modulation device. In widely known liquid crystal devices, a liquid crystal layer is provided between a pair of substrates opposing each other. Additionally, it is common for such a liquid crystal device to include a polarizing element inputting a predetermined polarized light to the liquid crystal layer and an alignment film controlling alignment of liquid crystal molecules when no voltage is applied.
Among known polarizing elements, there are a thin-film polarizing element and a wire-grid polarizing element. The thin-film polarizing element is produced by extending a film made of resin containing iodine or a dichroic dye in a single direction to allow molecules of iodine or the dichroic dye to be aligned in the extension direction. The wire-grid polarizing element is formed by densely laying nano-scale metal thin wires on a substrate made of a transparent material.
The wire-grid polarizing element is made of an inorganic material. Thus, due to its excellent thermal resistance, the wire-grid polarizing element is suitably used particularly as a thermally-resistant constituent member, such as a polarizing element for a light valve of a liquid crystal projector. JP-A-2005-242379 discloses a structural example of the wire-grid polarizing element thus characterized.
As described above, the wire-grid polarizing element is excellent in thermal resistance as compared to a polarizing element made of an organic material, but tends to deteriorate due to oxidization of metal thin wires. For example, when a liquid crystal projector including a wire-grid polarizing element is continuously used for a long hour, the polarizing element continues to intercept light from a light source for the long hour and thus, heat storage occurs in the polarizing element. As a result, the oxidization of the metal thin wires is accelerated, thereby promoting deterioration. In order to prevent the oxidization, there is also proposed a technique for coating the metal thin wires with a different material for protection.
On the other hand, optical characteristics of the polarizing element are influenced by a refractive index of a material provided around the metal thin wires, so that a material with a refractive index of 1 seems to be desirable. In other words, it is desirable to place the metal thin wires in an air (or a vacuum). In this case, however, optical characteristics seem to be reduced when a region between the metal thin wires is completely filled with a protection material to protect the polarizing element.